To support stack unwinding for cancellation points, add -fexceptions flag

for them, two functions _pthread_cancel_enter and _pthread_cancel_leave
are added to let thread enter and leave a cancellation point, it also
makes it possible that other functions can be cancellation points in
libraries without having to be rewritten in libthr.

14 files changed, 75 insertions, 72 deletions

diff --git a/lib/libc/Makefile b/lib/libc/Makefile
index dae4db3..3cff71f 100644
--- a/lib/libc/Makefile
+++ b/lib/libc/Makefile
@@ -31,6 +31,11 @@ CLEANFILES+=tags
 INSTALL_PIC_ARCHIVE=
 PRECIOUSLIB=
 
+.ifndef NO_THREAD_STACK_UNWIND
+CANCELPOINTS_CFLAGS=-fexceptions
+CFLAGS+=${CANCELPOINTS_CFLAGS}
+.endif
+
 #
 # Only link with static libgcc.a (no libgcc_eh.a).
 #
@@ -145,3 +150,5 @@ CWARNFLAGS:=	${.IMPSRC:Ngdtoa_*.c:C/^.+$/${CWARNFLAGS}/:C/^$/-w/}
 SSP_CFLAGS:=	${SSP_CFLAGS:S/^-fstack-protector-all$/-fstack-protector/}
 # Disable stack protection for SSP symbols.
 SSP_CFLAGS:=	${.IMPSRC:N*/stack_protector.c:C/^.+$/${SSP_CFLAGS}/}
+# Generate stack unwinding tables for cancellation points
+CANCELPOINTS_CFLAGS:=	${.IMPSRC:Mcancelpoints_*:C/^.+$/${CANCELPOINTS_CFLAGS}/:C/^$//}
diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index dd4bb5a..32888dd 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -25,7 +25,7 @@ SRCS+=  __getosreldate.c __xuname.c \
 	pause.c pmadvise.c popen.c posix_spawn.c \
 	psignal.c pututxline.c pw_scan.c pwcache.c \
 	raise.c readdir.c readpassphrase.c rewinddir.c \
-	scandir.c seed48.c seekdir.c sem.c sem_new.c semctl.c \
+	scandir.c seed48.c seekdir.c semctl.c \
 	setdomainname.c sethostname.c setjmperr.c setmode.c \
 	setproctitle.c setprogname.c siginterrupt.c siglist.c signal.c \
 	sigsetops.c sleep.c srand48.c statvfs.c stringlist.c strtofflags.c \
@@ -35,6 +35,14 @@ SRCS+=  __getosreldate.c __xuname.c \
 	usleep.c utime.c utxdb.c valloc.c vis.c wait.c wait3.c waitpid.c \
 	wordexp.c
 
+CANCELPOINTS_SRCS=sem.c sem_new.c
+.for src in ${CANCELPOINTS_SRCS}
+SRCS+=cancelpoints_${src}
+CLEANFILES+=cancelpoints_${src}
+cancelpoints_${src}:
+	ln -sf ${.CURDIR}/gen/${src} ${.TARGET}
+.endfor
+
 SYM_MAPS+=${.CURDIR}/gen/Symbol.map
 
 # machine-dependent gen sources
diff --git a/lib/libc/gen/Symbol.map b/lib/libc/gen/Symbol.map
index 6bd3140..dd375b0 100644
--- a/lib/libc/gen/Symbol.map
+++ b/lib/libc/gen/Symbol.map
@@ -403,6 +403,8 @@ FBSDprivate_1.0 {
 	_pthread_attr_setstackaddr;
 	_pthread_attr_setstacksize;
 	_pthread_cancel;
+	_pthread_cancel_enter;
+	_pthread_cancel_leave;
 	_pthread_cleanup_pop;
 	_pthread_cleanup_push;
 	_pthread_cond_broadcast;
diff --git a/lib/libc/gen/_pthread_stubs.c b/lib/libc/gen/_pthread_stubs.c
index 044e299e..355b904 100644
--- a/lib/libc/gen/_pthread_stubs.c
+++ b/lib/libc/gen/_pthread_stubs.c
@@ -121,6 +121,8 @@ pthread_func_entry_t __thr_jtable[PJT_MAX] = {
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_TESTCANCEL */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_CLEANUP_POP_IMP */
 	{PJT_DUAL_ENTRY(stub_zero)},    /* PJT_CLEANUP_PUSH_IMP */
+	{PJT_DUAL_ENTRY(stub_zero)},	/* PJT_CANCEL_ENTER */
+	{PJT_DUAL_ENTRY(stub_zero)},	/* PJT_CANCEL_LEAVE */
 };
 
 /*
@@ -269,6 +271,8 @@ STUB_FUNC2(pthread_setcanceltype, PJT_SETCANCELTYPE, int, int, void *)
 STUB_FUNC(pthread_testcancel, PJT_TESTCANCEL, void)
 STUB_FUNC1(__pthread_cleanup_pop_imp, PJT_CLEANUP_POP_IMP, int, int)
 STUB_FUNC2(__pthread_cleanup_push_imp, PJT_CLEANUP_PUSH_IMP, void, void*, void *);
+STUB_FUNC1(_pthread_cancel_enter, PJT_CANCEL_ENTER, int, int)
+STUB_FUNC1(_pthread_cancel_leave, PJT_CANCEL_LEAVE, int, int)
 
 static int
 stub_zero(void)
diff --git a/lib/libc/gen/sem.c b/lib/libc/gen/sem.c
index 628e650..e9ae669 100644
--- a/lib/libc/gen/sem.c
+++ b/lib/libc/gen/sem.c
@@ -312,21 +312,6 @@ _libc_sem_unlink_compat(const char *name)
 }
 
 static int
-enable_async_cancel(void)
-{
-	int old;
-
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &old);
-	return (old);
-}
-
-static void
-restore_async_cancel(int val)
-{
-	_pthread_setcanceltype(val, NULL);
-}
-
-static int
 _umtx_wait_uint(volatile unsigned *mtx, unsigned id, const struct timespec *timeout)
 {
 	if (timeout && (timeout->tv_sec < 0 || (timeout->tv_sec == 0 &&
@@ -371,15 +356,15 @@ _libc_sem_timedwait_compat(sem_t * __restrict sem,
 	const struct timespec * __restrict abstime)
 {
 	struct timespec ts, ts2;
-	int val, retval, saved_cancel;
+	int val, retval;
 
 	if (sem_check_validity(sem) != 0)
 		return (-1);
 
 	if ((*sem)->syssem != 0) {
-		saved_cancel = enable_async_cancel();
-		retval = ksem_wait((*sem)->semid);
-		restore_async_cancel(saved_cancel);
+		_pthread_cancel_enter(1);
+		retval = ksem_wait((*sem)->semid); /* XXX no timeout */
+		_pthread_cancel_leave(retval == -1);
 		return (retval);
 	}
 
@@ -390,8 +375,10 @@ _libc_sem_timedwait_compat(sem_t * __restrict sem,
 			if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
 				return (0);
 		}
-		if (retval)
+		if (retval) {
+			_pthread_testcancel();
 			break;
+		}
 		if (abstime) {
 			if (abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0) {
 				errno = EINVAL;
@@ -402,9 +389,9 @@ _libc_sem_timedwait_compat(sem_t * __restrict sem,
 		}
 		atomic_add_int(&(*sem)->nwaiters, 1);
 		pthread_cleanup_push(sem_cancel_handler, sem);
-		saved_cancel = enable_async_cancel();
+		_pthread_cancel_enter(1);
 		retval = _umtx_wait_uint(&(*sem)->count, 0, abstime ? &ts2 : NULL);
-		restore_async_cancel(saved_cancel);
+		_pthread_cancel_leave(0);
 		pthread_cleanup_pop(0);
 		atomic_add_int(&(*sem)->nwaiters, -1);
 	}
diff --git a/lib/libc/gen/sem_new.c b/lib/libc/gen/sem_new.c
index ef4ba68..2698b40 100644
--- a/lib/libc/gen/sem_new.c
+++ b/lib/libc/gen/sem_new.c
@@ -47,6 +47,7 @@
 #include <semaphore.h>
 #include <unistd.h>
 #include "un-namespace.h"
+#include "libc_private.h"
 
 __weak_reference(_sem_close, sem_close);
 __weak_reference(_sem_destroy, sem_destroy);
@@ -364,15 +365,6 @@ _sem_trywait(sem_t *sem)
 	return (-1);
 }
 
-static void
-sem_cancel_handler(void *arg)
-{
-	sem_t *sem = arg;
-
-	if (sem->_kern._has_waiters && sem->_kern._count)
-		usem_wake(&sem->_kern);
-}
-
 #define TIMESPEC_SUB(dst, src, val)                             \
         do {                                                    \
                 (dst)->tv_sec = (src)->tv_sec - (val)->tv_sec;  \
@@ -384,27 +376,12 @@ sem_cancel_handler(void *arg)
         } while (0)
 
 
-static __inline int
-enable_async_cancel(void)
-{
-	int old;
-
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &old);
-	return (old);
-}
-
-static __inline void
-restore_async_cancel(int val)
-{
-	_pthread_setcanceltype(val, NULL);
-}
-
 int
 _sem_timedwait(sem_t * __restrict sem,
 	const struct timespec * __restrict abstime)
 {
 	struct timespec ts, ts2;
-	int val, retval, saved_cancel;
+	int val, retval;
 
 	if (sem_check_validity(sem) != 0)
 		return (-1);
@@ -416,8 +393,10 @@ _sem_timedwait(sem_t * __restrict sem,
 				return (0);
 		}
 
-		if (retval)
+		if (retval) {
+			_pthread_testcancel();
 			break;
+		}
 
 		/*
 		 * The timeout argument is only supposed to
@@ -431,11 +410,9 @@ _sem_timedwait(sem_t * __restrict sem,
 			clock_gettime(CLOCK_REALTIME, &ts);
 			TIMESPEC_SUB(&ts2, abstime, &ts);
 		}
-		pthread_cleanup_push(sem_cancel_handler, sem);
-		saved_cancel = enable_async_cancel();
+		_pthread_cancel_enter(1);
 		retval = usem_wait(&sem->_kern, abstime ? &ts2 : NULL);
-		restore_async_cancel(saved_cancel);
-		pthread_cleanup_pop(0);
+		_pthread_cancel_leave(0);
 	}
 	return (retval);
 }
diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
index c5f6eb3..a4737fe 100644
--- a/lib/libc/include/libc_private.h
+++ b/lib/libc/include/libc_private.h
@@ -129,6 +129,8 @@ typedef enum {
 	PJT_TESTCANCEL,
 	PJT_CLEANUP_POP_IMP,
 	PJT_CLEANUP_PUSH_IMP,
+	PJT_CANCEL_ENTER,
+	PJT_CANCEL_LEAVE,
 	PJT_MAX
 } pjt_index_t;
 
@@ -217,4 +219,7 @@ int _elf_aux_info(int aux, void *buf, int buflen);
 struct dl_phdr_info;
 int __elf_phdr_match_addr(struct dl_phdr_info *, void *);
 
+void	_pthread_cancel_enter(int);
+void	_pthread_cancel_leave(int);
+
 #endif /* _LIBC_PRIVATE_H_ */
diff --git a/lib/librt/Makefile b/lib/librt/Makefile
index f98d94e..86be751 100644
--- a/lib/librt/Makefile
+++ b/lib/librt/Makefile
@@ -3,14 +3,15 @@
 LIB=rt
 SHLIB_MAJOR= 1
 CFLAGS+=-I${.CURDIR}/../libc/include -I${.CURDIR}
+.ifndef NO_THREAD_STACK_UNWIND
+CFLAGS+=-fexceptions
+.endif
 CFLAGS+=-Winline -Wall -g
 DPADD=	${LIBPTHREAD}
 LDADD=	-lpthread
 
 WARNS?=	2
 
-#MAN=	libthr.3
-
 SRCS+= aio.c mq.c sigev_thread.c timer.c
 
 PRECIOUSLIB=
diff --git a/lib/librt/mq.c b/lib/librt/mq.c
index f2e01ca..750e969 100644
--- a/lib/librt/mq.c
+++ b/lib/librt/mq.c
@@ -39,6 +39,7 @@
 #include <signal.h>
 #include "sigev_thread.h"
 #include "un-namespace.h"
+#include "libc_private.h"
 
 extern int	__sys_kmq_notify(int, const struct sigevent *);
 extern int	__sys_kmq_open(const char *, int, mode_t,
@@ -200,12 +201,11 @@ ssize_t
 __mq_timedreceive_cancel(mqd_t mqd, char *buf, size_t len,
 	unsigned *prio, const struct timespec *timeout)
 {
-	int oldtype;
 	int ret;
 
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldtype);
+	_pthread_cancel_enter(1);
 	ret = __sys_kmq_timedreceive(mqd->oshandle, buf, len, prio, timeout);
-	_pthread_setcanceltype(oldtype, NULL);
+	_pthread_cancel_leave(ret == -1);
 	return (ret);
 }
 
@@ -219,12 +219,11 @@ __mq_receive(mqd_t mqd, char *buf, size_t len, unsigned *prio)
 ssize_t
 __mq_receive_cancel(mqd_t mqd, char *buf, size_t len, unsigned *prio)
 {
-	int oldtype;
 	int ret;
 
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldtype);
+	_pthread_cancel_enter(1);
 	ret = __sys_kmq_timedreceive(mqd->oshandle, buf, len, prio, NULL);
-	_pthread_setcanceltype(oldtype, NULL);
+	_pthread_cancel_leave(ret == -1);
 	return (ret);
 }
 ssize_t
@@ -239,12 +238,11 @@ ssize_t
 __mq_timedsend_cancel(mqd_t mqd, char *buf, size_t len,
 	unsigned prio, const struct timespec *timeout)
 {
-	int oldtype;
 	int ret;
 
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldtype);
+	_pthread_cancel_enter(1);
 	ret = __sys_kmq_timedsend(mqd->oshandle, buf, len, prio, timeout);
-	_pthread_setcanceltype(oldtype, NULL);
+	_pthread_cancel_leave(ret == -1);
 	return (ret);
 }
 
@@ -259,12 +257,11 @@ __mq_send(mqd_t mqd, char *buf, size_t len, unsigned prio)
 ssize_t
 __mq_send_cancel(mqd_t mqd, char *buf, size_t len, unsigned prio)
 {
-	int oldtype;
 	int ret;
 
-	_pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldtype);
+	_pthread_cancel_enter(1);
 	ret = __sys_kmq_timedsend(mqd->oshandle, buf, len, prio, NULL);
-	_pthread_setcanceltype(oldtype, NULL);
+	_pthread_cancel_leave(ret == -1);
 	return (ret);
 }
 
diff --git a/lib/libthr/Makefile b/lib/libthr/Makefile
index 8b7af3a..a51b446 100644
--- a/lib/libthr/Makefile
+++ b/lib/libthr/Makefile
@@ -26,9 +26,7 @@ CFLAGS+=-I${.CURDIR}/../../libexec/rtld-elf/${MACHINE_CPUARCH}
 CFLAGS+=-I${.CURDIR}/../libthread_db
 CFLAGS+=-Winline
 
-LIBTHR_UNWIND_STACK=yes
-
-.ifdef LIBTHR_UNWIND_STACK
+.ifndef NO_THREAD_UNWIND_STACK
 CFLAGS+=-I${.CURDIR}/../../contrib/gcc -fexceptions 
 CFLAGS+=-D_PTHREAD_FORCED_UNWIND
 .endif
diff --git a/lib/libthr/pthread.map b/lib/libthr/pthread.map
index bcb5c08..5e36239 100644
--- a/lib/libthr/pthread.map
+++ b/lib/libthr/pthread.map
@@ -246,6 +246,8 @@ FBSDprivate_1.0 {
 	_pthread_attr_setstackaddr;
 	_pthread_attr_setstacksize;
 	_pthread_cancel;
+	_pthread_cancel_enter;
+	_pthread_cancel_leave;
 	_pthread_cleanup_pop;
 	_pthread_cleanup_push;
 	_pthread_cond_broadcast;
diff --git a/lib/libthr/thread/thr_cancel.c b/lib/libthr/thread/thr_cancel.c
index cd456b7..89f0ee1 100644
--- a/lib/libthr/thread/thr_cancel.c
+++ b/lib/libthr/thread/thr_cancel.c
@@ -162,3 +162,15 @@ _thr_cancel_leave(struct pthread *curthread, int maycancel)
 	    !THR_IN_CRITICAL(curthread) && maycancel))
 		_pthread_exit(PTHREAD_CANCELED);
 }
+
+void
+_pthread_cancel_enter(int maycancel)
+{
+	_thr_cancel_enter2(_get_curthread(), maycancel);
+}
+
+void
+_pthread_cancel_leave(int maycancel)
+{
+	_thr_cancel_leave(_get_curthread(), maycancel);
+}
diff --git a/lib/libthr/thread/thr_init.c b/lib/libthr/thread/thr_init.c
index 56541a8..e8a01d3 100644
--- a/lib/libthr/thread/thr_init.c
+++ b/lib/libthr/thread/thr_init.c
@@ -248,7 +248,9 @@ static pthread_func_t jmp_table[][2] = {
 	{DUAL_ENTRY(_pthread_sigmask)},		/* PJT_SIGMASK */
 	{DUAL_ENTRY(_pthread_testcancel)},	/* PJT_TESTCANCEL */
 	{DUAL_ENTRY(__pthread_cleanup_pop_imp)},/* PJT_CLEANUP_POP_IMP */
-	{DUAL_ENTRY(__pthread_cleanup_push_imp)}/* PJT_CLEANUP_PUSH_IMP */
+	{DUAL_ENTRY(__pthread_cleanup_push_imp)},/* PJT_CLEANUP_PUSH_IMP */
+	{DUAL_ENTRY(_pthread_cancel_enter)},	/* PJT_CANCEL_ENTER */
+	{DUAL_ENTRY(_pthread_cancel_leave)}		/* PJT_CANCEL_LEAVE */
 };
 
 static int init_once = 0;
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index a42b4ec..e5a82b9 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -716,7 +716,8 @@ int	_sched_yield(void);
 void	_pthread_cleanup_push(void (*)(void *), void *);
 void	_pthread_cleanup_pop(int);
 void	_pthread_exit_mask(void *status, sigset_t *mask) __dead2 __hidden;
-
+void	_pthread_cancel_enter(int maycancel);
+void 	_pthread_cancel_leave(int maycancel);
 
 /* #include <fcntl.h> */
 #ifdef  _SYS_FCNTL_H_